• Title/Summary/Keyword: Marking

Search Result 943, Processing Time 0.025 seconds

A Comparison of Methods for Estimating the Productivity of Zostera marina

  • Park, Sang-Rul;Li, Wen-Tao;Kim, Seung-Hyeon;Kim, Jae-Woo;Lee, Kun-Seop
    • Journal of Ecology and Environment
    • /
    • v.33 no.1
    • /
    • pp.59-65
    • /
    • 2010
  • Because seagrass production significantly contributes to the biodiversity and production of coastal and estuarine ecosystems, accurate estimation of seagrass productivity is a critical step toward understanding the ecological roles of seagrass in these ecosystems. To develop an accurate and effective method of measuring seagrass productivity, we estimated leaf productivity of eelgrass (Zostera marina) on the southern coast of Korea using three methods, the conventional leaf marking method, the elongation-mass method (Short '87 method), and the plastochrone method. In each season, shoots were pierced through the bundle sheath using a hypodermic needle and were collected after 2-4 weeks had elapsed to estimate their productivity. The leaf elongation and the leaf plastochrone intervals varied significantly among seasons. On an annual basis, the conventional leaf marking method showed the lowest leaf productivity estimates compared to the elongation-mass method and the plastochrone method, suggesting that the conventional leaf marking method underestimated leaf productivity as it ignored leaf maturation processes and new leaf growth within the sheath. Since the elongation-mass method considered leaf maturation processes, this method produced higher leaf productivity estimates than the conventional leaf marking method. On an annual basis, the plastochrone method produced the highest leaf productivity estimates. Below-ground productivity, which can be easily estimated using the plastochrone method, ranged between 3.29 and 5.73 (mg dry weight $shoot^{-1}\;day^{-1}$) and accounted for about 17.8% to 30.3% of total productivity. Because of the high contributions of below-ground productivity to total seagrass production, we suggest that the plastochrone method is an effective and simple technique for assessing both above- and below-ground productivities.

A Study on Retroreflectivities of Pavement Markings by Freeway Facility Types (고속도로 시설물별 차선반사도 다양성 연구)

  • Oh, Heung-Un
    • International Journal of Highway Engineering
    • /
    • v.7 no.4 s.26
    • /
    • pp.173-184
    • /
    • 2005
  • Pavement markings delineate driver's sight and attentions at day and night. Retroreflectivities of the pavement markings are known to be affected by some factors such as geometrical characteristics of road sections, marking materials, traffic volumes, weather, and so on. Therefore, pavement markings would have different retroreflectivities place by place. The objective of this paper is to contend that there are rises and falls of retroreflectivity of specific geometrical characteristics of road section based on observed field data. For this purpose, retroreflectivities of yellow continued lines and white skip lines were measured on the freeway sections from Hanam to Nami interchanges. And then, the sections are categorized based on road geometric or facility types. From this study, it may be concluded that there exist considerably lower retroreflectivity trends of pavement markings at sharply curved sections, climbing lane sections, ramp sections, and tunnel sections than averaged retroreflectivity trends on freeway sections. This may leads to the necessity of differential pavement marking managements.

  • PDF

Improving Lane Marking Detection by Combining Horizontal 1-D LoG Filtered Scale Space and Variable Thresholding (수평 1-D LoG 필터링 스케일 공간과 가변적 문턱처리의 결합에 의한 차선 마킹 검출 개선)

  • Yoo, Hyeon-Joong
    • Journal of the Institute of Electronics Engineers of Korea SP
    • /
    • v.49 no.4
    • /
    • pp.85-94
    • /
    • 2012
  • Lane marking detection is essential to both ITS and DAS systems. The objective of this paper is to provide more robust technique for lane marking detection than traditional techniques by using scale-space technique. Variable thresholding that is based on the local statistics may be very effective for detecting such objects as lane markings that have prominent intensities. However, such techniques that only rely on local statistics have limitations containing irrelevant areas as well. We reduce the candidate areas by combining the variable thresholding result with cost-efficient horizontal 1D LoG filtered scale space. Through experiments using practical images, we could achieve significant improvement over the techniques based not only on the variable thresholding but also on the Hough transform that is another very popular technique for this purpose.

The Awareness and Countermeasures against Harmful Effect of Passive Smoking in Korean Adult (일부 성인의 간접흡연에 대한 인식도 및 대책)

  • Sim, Hong-Seok;Hong, Hyun-Sook;Meng, Kwang-Ho;Lee, Kang-Sook
    • Journal of Preventive Medicine and Public Health
    • /
    • v.33 no.1
    • /
    • pp.91-98
    • /
    • 2000
  • Objectives : This study is to evaluate the awareness, attitude, practice and the countermeasures against passive smoking in Korean adults. Methods : By self-administered questionnaires, we assessed the knowledge, attitude, behavior for passive smoking and the countermeasure for reduction of it's harmful effects in 289 men and 238 women. Results : The subjects that have heard about passive smoking were 96.8% in total and well known were 26.4% of current smoker, 56.6% of ex-smoker, and 14.8% of non-smoker(p=0.001). The irritative symptom from passive smoking was the most frequent in non-smokers and the most common place where exposed to passive smoking was public place. For attitude against passive smoking in 'no smoking allowed area', ex-smokers were the most active to recommend to stop smoking. And for opinion about establishment of 'no smoking allowed area', the restriction by law was the best acceptable method in smokers, exsmokers, and nonsmokers. In marking of 'no smoking allowed area', 69.9% of smokers answered no smoking, but in non-marking area only 6.3% stop smoking. When smokers were recommended to stop smoking, the more subjects stop smoking with good feeling in marking area, but the less in non-marking area. The factor associated the high awareness of passive smoking were aged(OR=1.07, 1.03-1.12), men(OR=4.34, 2.32-8.46). The persons who have known well about passive smoking had good attitude and behavior to prevent of harmful effect of passive smoking. Conclusions : This study suggested that education program would be necessary to reduce the passive smoking.

  • PDF

High Performance Glass Beads for Traffic Marking in Wet Weather (차선의 우천시 야간 시인성 향상을 위한 그라스 비드 적용 연구)

  • Lee, Chang-Geun;Lee, Hyun-Seock;Oh, Heung-Un
    • International Journal of Highway Engineering
    • /
    • v.14 no.1
    • /
    • pp.9-16
    • /
    • 2012
  • The performance of road markings is classified into the visibility at daytime, night time, wet condition and rainy conditions. The objective of this study is to obtain the driving safety of drivers under conditions of unstable weather condition such as the rain. The visibility of road markings is closely related to the preview time and detection distances and the ways to improve road marking materials and increase the dry retroreflectivity and wet retroreflectivity, which are the measures of daytime and nighttime visibility is researched to decrease the traffic accidents. For this purpose, Road marking glass beads with the refraction rate of 1.5 and 2.2 are introduced to raise the retroreflectivity. After investigating the minimum threshold retroreflectivity and Install Minimum retroreflectivity at home and abroad, minimum control values for the roadmarking visibility and improvement of nightime rainy retroreflectivity are suggested by physical properties and retroreflectivity experiments.